Intravertebral discs, which separate and cushion the individual vertebrae of the human spine from each other, allow for the flexibility of the spine while still providing structural support. The intravertebral discs are often subject to degeneration with age, resulting in herniations, displacements, or other dysfunctions, thereby causing severe pain and lowering the quality of life. Artificial disc surgery, one preferred method of addressing this problem, involves the removal of the damaged disc and replacing it with an implant. This requires a surgical procedure in which the vertebrae adjacent to the damaged disc are separated (distracted), the damaged disc is removed, and an implant is positioned into the space between the distracted device.
Prior art spinal distraction instruments and spinal implant insertion instruments are known to those skilled in the art. For instance, a conventional spinal distraction device typically consists of two first class levers, hinged together to provide a spreading force at the distal end placed between the vertebrae when a spreading force is applied at the proximal end. Such a distraction device functions similarly to a pair of pliers.
A problem with this technology has been the danger of damaging surrounding soft tissues, especially the vulnerable nerve roots, during the distraction and implantation procedure. Therefore, what is required is solution that protects the soft tissue from being pinched or damaged.
Another problem with this technology has been that a clear passageway for the implantable procedure is not defined. Therefore, what is also required is a solution that provides for a clear implantation path while the vertebrae remain in a distracted position without significant obstruction of the working space. This also allows for a much shorter surgical procedure due to a more efficient means of implantation.
One unsatisfactory approach, in an attempt to solve the above-discussed problems is shown in FIGS. 1A and 1B, which shows a conventional distraction and implantation surgical device 100. Device 100 consists of two arms 102 and 104, each ending in a pair of fingers, 106, and 108, respectively. The fingers are inserted between two vertebrae, and distraction occurs by applying squeezing pressure between the lower arm 104 and a third arm 110 shown in FIG. 1B. The force is transferred to the upper arm through projection 112, resulting in the separation of fingers 106 and 108, and in turn the distraction of the spine. However, a disadvantage of this approach is that it does not adequately protect the soft tissues from damage.
Another disadvantage of the conventional instrument shown in FIGS. 1A-1B is the inability to finely tune the distraction distance and to adjust for spinal curvature during the distraction of the vertebrae. Therefore, what is also needed is a solution that addresses these needed functions.
Heretofore, the requirements of protecting the soft tissues from damage during distraction of the vertebrae and the implantation of a graft, providing a clear implantation path, and providing a finely tunable distraction that is able to adjust for spinal curvature referred to above have not been fully met in a surgical instrument. What is needed is a solution that simultaneously solves all of these problems.